California Gov. Gavin Newsom announced Friday that the state will require all schoolchildren to get vaccinated against coronavirus in the coming year, setting the stage for the nation’s most sweeping vaccine mandate for young people.

The mandate will take effect gradually after the Food and Drug Administration gives full approval to a coronavirus vaccine for younger children. None have been authorized yet, even under emergency status, for children under the age of 12.

The Pfizer-BioNTech vaccine has been authorized for emergency use for 12-to-15-year-olds, and has been fully approved for people 16 and older. The state said that it could begin requiring a coronavirus vaccine for students in grades 7 to 12 starting in July.

At that point, it will become part of the slate of vaccines California requires children to get before stepping into classrooms. It will apply to any student who wants to attend school — public or private — in-person.

“Our schools already require vaccines for measles, mumps and more,” Newsom (D) wrote on Twitter. “Why? Because vaccines work. This is about keeping our kids safe & healthy.”

Over the summer, the Puerto Rico Department of Education became one of the first school districts to mandate a coronavirus vaccine for students over the age of 12. Los Angeles Unified, the nation’s second largest school district, passed a similar requirement in September, along with the school district in nearby Culver City.

But California is the first state to preemptively require vaccination for all schoolchildren, and may pave the way for it to become a school requirement elsewhere.

In September, Pfizer-BioNTech said its vaccine triggered a robust immune response in younger children. Here’s what we know so far. (Drea Cornejo/The Washington Post)

Pediatricians and parents have eagerly awaited approval of a coronavirus vaccine for younger children, particularly as the highly contagious delta variant proliferates in classrooms, pushing children and staff into quarantine and forcing schools to close.The Centers for Disease Control and Prevention has calculated that more than 900,000 students have been impacted by closures since the start of the school year. Coronavirus cases among children have risen to record levels, making up nearly 30 percent of cases in the first week of September.

While children generally do not get seriously ill from the coronavirus and deaths are rare, some require hospitalization and can experience long-term symptoms. But even with low-level symptoms, they can spread the virus, passing it on to members of their household or school staff. A vaccine for children could tamp down on infections inside classrooms and reduce community spread.

California has some of the strictest vaccine requirements, and is among only a handful of states that do not allow parents to opt their children out of inoculations for religious or “personal beliefs” reasons, according to the National Conference of State Legislatures, which means few families may have the option to forgo a coronavirus vaccine.

More than 85 percent of California adults have received at least one dose of a coronavirus vaccine, according to data compiled by The Washington Post.

But there are vocal groups of parents who oppose the vaccine mandate, calling it an overreach and arguing that they should get to decide if their children get vaccinated.

Celeste Fiehler, an activist with ParentUnion.org and the conservative California Policy Center, said she is opposed to the mandate and plans to pull her children from school when it takes effect. She has organized a webinar to help parents organize their own “pods,” where they can home-school their children alongside others and even hire their own teachers.

“I just don’t feel that there’s enough study when it comes to kids,” said Fiehler, who lives near Palm Springs. “I’m not ready.”

Vanessa Aramayo, the executive director of the Los Angeles-based Latino advocacy group Alliance for a Better Community, said she backs the mandate. Latino children have higher rates of infection than children of other racial groups in part because their parents are more likely to be front line workers.

“We need to make sure that we’re doing what we can to keep our children healthy,” said Aramayo. And as the mother of 6-year-old twins, she said she is eager to get them vaccinated. “The kids don’t have that protection, so once they do there will be added relief.”